Phenolic amides and their use as stabilizers

ABSTRACT

Phenolic amides, useful as stabilizers for organic materials such as polyols and polyurethanes, possess the general formula ##STR1## wherein n is 0 to 3, R 1  is alkyl of from 1 to about 6 carbon atoms, R 2  is hydrogen or alkyl of from 1 to about 6 carbon atoms, R 3  is hydrogen or hydrocarbyl of up to about 20 carbon atoms, optionally containing one or more heterocyclic groups, R 4  is hydrocarbyl of up to about 20 carbon atoms, optionally containing one or more heterocyclic groups, or R 3  and R 4  together with the nitrogen atom to which they are bonded are joined together to form a heterocyclic group, optionally containing one or more additional heterocyclic atoms.

This is a divisional application of Ser. No. 08/839,694 filed Apr. 15,1997, is now U.S. Pat. No. 5,917,044.

BACKGROUND OF THE INVENTION

This invention relates to phenolic amides and the use of the amides asstabilizers for polymers such as polyols and/or polyurethane foams.

The stabilization of polyalkylene polyether polyols and other polymericmaterials with antioxidants or other stabilizers and the use of thestabilized polyols in the preparation of polyurethane foams to inhibitscorch are well known to those skilled in the art. Polyether polyolsused in the manufacture of slabstock flexible urethane foam aretypically stabilized with antioxidant packages consisting of phenolicand amine antioxidants and may also contain the synergist phenothiazineor a phosphate moiety.

Illustrating such stabilization are U.S. Pat. Nos. 3,567,664 and3,637,865 which disclose polyurethane foams stabilized with a mixture of2,6-di-tert-butyl-4-methyl phenol [butylated hydroxy toluene (BHT)] andp,p'-dialkyldiphenylamines.

BHT (2,6-di-t-butyl-4-methyl phenol) is the most common and widely usedhindered phenolic stabilizer for polyolefins, styrenics, vinyls, andelastomers. However, there are problems associated with the use of BHTsuch as long term discoloration, high volatility, sublimation, anddifficulty of use due to its solid form. Hindered 2,6-di-t-butylphenolics with various larger aliphatic groups replacing the methylgroup in the para-position of the BHT ring have succeeded in reducingvolatility, but usually at the expense of a reduction of activity of theantioxidant, as the more substituted compounds contain relatively lessof the hindered hydroxy groups which provide the stabilization activityof hindered phenolic stabilizers.

SUMMARY OF THE INVENTION

In accordance with the present invention, phenolic amides are providedwhich possess the general formula ##STR2## wherein n is 0 to 3, R₁ isalkyl of from 1 to about 6 carbon atoms, R₂ is hydrogen or alkyl of from1 to about 6 carbon atoms, R₃ is hydrogen or hydrocarbyl of up to about20 carbon atoms, optionally containing one or more heterocyclic groups,R₄ is hydrocarbyl of up to about 20 carbon atoms, optionally containingone or more heterocyclic groups, or R₃ and R₄ together with the nitrogenatom to which they are bonded are joined together to form a heterocyclicgroup, optionally containing one or more additional heterocyclic atoms.

The foregoing phenolic amides are useful as stabilizers of organicmaterials, e.g., polyether polyols to be used in the manufacture offlexible and semiflexible polyurethane foam, which are subject tothermal and oxidative deterioration or degradation caused by heat orlight. When added to the polyols and/or directly to the polyurethanefoam-forming reaction mixture containing such polyols, the phenolicamide stabilizers inhibit scorch in the polyurethane foam product.

Many of the phenolic amide stabilizers of this invention are lessvolatile than BHT and as such are less likely to escape into theenvironment than the latter. Compared to the known esters, the amides ofthis invention are more resistant to hydrolytic degradation, anadvantageous property in those applications where water/moisture may bepresent. The phenolic amides of this invention possessing one or moreamine groups exhibit greater solubility compared with the prior artesters possessing long alkyl chains and are therefore especiallyadvantageous for use in stabilizing polar materials.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The phenolic amides of this invention are obtained by reacting aphenolic acid or derivative thereof of the general formula ##STR3##wherein n, R₁ and R₂ have the aforestated meanings and Y is alkoxy offrom 1 to about 20 carbon atoms, hydroxy or halogen, with a primary orsecondary alkyl amine of the general formula ##STR4## wherein R₃ and R₄have the aforestated meanings.

Many of the starting phenolic acid compounds and their derivatives arewell known. See, e.g., U.S. Pat. Nos. 3,247,240, 3,330,859, 3,364,250,3,642,868, 3,644,482, 3,801,540, 3,840,585, 4,085,132, 4,228,297,4,529,809, 4,659,863, 5,089,656, 5,130,465, 5,264,612, and Re. 27,004,the contents of which are incorporated by reference herein. A preferredstarting phenolic acid derivative for reaction with a primary orsecondary alkyl amine of this invention is methyl3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate.

Suitable amines for reaction with the foregoing phenolic acids and/orderivatives thereof to provide the phenolic amides of this invention areprimary or secondary alkyl amines of aliphatic, cycloaliphatic oraromatic structure optionally containing one or more heteroatoms such asnitrogen, oxygen and/or sulfur. Specific amines include those in whichR₃ and R₄ are independently selected to be methyl, ethyl, propyl,isopropyl, butyl, isobutyl, pentyl, hexyl, cyclohexyl, heptyl, octyl,2-ethylhexyl, nonyl, decyl, dodecyl, stearyl, oleyl, phenyl, benzyl, andthe like, containing e.g., up to about 20 carbon atoms, preferably nomore than about 18 carbon atoms and more preferably no more than about12 carbon atoms. Useful amines in which R₃ and R₄ together with thenitrogen atom to which they are bonded are joined together to form aheterocyclic compound include cyclic amines such as pyrrolidine,piperidine, piperazine, morpholine, and the like. Also useful are aminesin which R₃ and/or R4 are alkyl groups substituted with one or moreheterocyclic substituents. Examples of such amines are2-(2-aminoethyl)-1-methylpyrrolidine, 4-(2-aminoethyl)-morpholine,1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)-piperidine,1-(2-aminoethyl)piperazine, and the like. Still other useful amines are(aminoalkyl)alkylamines such as N-alkylethylene diamines,N-alkyl-1,3-propane diamines, and the like.

The phenolic amides of this invention are obtained by reacting thephenolic acid or derivative thereof and the primary or secondary alkylamine in the presence of a suitable catalyst, e.g., p-toluene sulfonicacid. The reaction is advantageously conducted in a subsurface gas purgesuch as nitrogen. A preferred temperature for this reaction is fromabout 110° C. to about 250° C. and more preferably from about 130° C. toabout 180° C.

The phenolic amides of this invention are useful as stabilizers fororganic materials that are susceptible to degradation, e.g.,deterioration due to oxidation, elevated temperature and/or exposure tolight or other actinic radiation. Examples of such organic materials aresynthetic organic polymers such as vinyl resins formed from thepolymerization of vinyl halides or from the copolymerization of vinylhalides with unsaturated polymerizable compounds. Examples of theseunsaturated polymerizable compounds include vinyl esters, alpha,beta-unsaturated acids, esters, aldehydes, or ketones, and unsaturatedhydrocarbons such as butadiene or styrene.

Additional materials stabilized by the phenolic amide stabilizers ofthis invention are poly-alpha-olefins such as polyethylene,polypropylene, polybutylene, and polyisoprene, copolymers ofpoly-alpha-olefins, polyamides, polyesters, polycarbonates, polyacetals,polystyrene, and polyethylenoxide. Also included are copolymers such ashigh-impact polystyrene containing copolymers of butadiene and styreneand those formed by the copolymerization of acrylonitrile, butadiene,and styrene.

Other materials also stabilized include aliphatic ester lubricatingoils, animal and vegetable-derived oils, hydrocarbon materials such asgasoline, diesel oil, mineral oil, fuel oil, drying oil, cutting fluids,waxes, resins, and fatty acids such as soaps.

The phenolic amides of this invention are particularly useful for thestabilization of polyether polyols and polyurethane foams derivedtherefrom. Stabilization is required to protect these materials fromoxidative degradation, particularly at the high temperature encounteredduring the reaction to make polyurethane foam. Polyether polyols arewell known in the art and are obtained by reacting polyhydric alcohols,e.g., those containing from 2-8 hydroxyl groups such as ethylene glycol,propylene glycol, diethylene glycol, 2,3-butylene glycol, 1,3-butyleneglycol, 1,5-pentane diol, glycerol, trimethylolpropane,triethylolpropane, sorbitol, pentaerythritol, and mixtures thereof, witha 1,2-epoxide, e.g., ethylene oxide, propylene oxide, butylene oxide,cyclohexane oxide, glycidol and mixtures thereof. The preferredpolyether polyols contain from 2-4 hydroxyl groups and are obtained byreacting one or more polyhydric alcohols having a like number ofhydroxyl groups with ethylene oxide, propylene oxide, butylene oxide,and mixtures thereof.

The phenolic amide stabilizer is added to the polyether polyol in anamount sufficient to impart an appreciable stabilizing effect. Ingeneral, this amount may vary from about 0.1 to about 2 weight percent,preferably from about 0.2 to about 1 weight percent and more preferablyfrom about 0.4 to about 0.6 weight percent by total weight of polyetherpolyol.

Where the polyether polyol is to be employed in the manufacture of apolyurethane foam, and stabilization of the polyol is not in issue, thestabilizer composition can be added to some other component of thepolyurethane-forming reaction mixture, e.g., to the polyisocyanate, theprepolymer, the foaming agent, etc., or to the reaction mixture onceformed, rather than to the polyol. In this case, the foregoing amountsof phenolic amide stabilizer calculated on the basis of the totalpolyether polyol component can be utilized,

Any suitable organic isocyanate which is capable of reacting with apolyol to form a polyurethane can be employed in preparing the foam.This includes diisocyanates and polyisocyanates, e.g., triisocyanatesand polymeric isocyanates. Due to their commercial availability, thepolymeric isocyanates and toluene diisocyanates are preferred. Thelatter, the use of which is more preferred, can be supplied in the formof an isomeric mixture of about 80 weight percent of the 2,4-isomer andabout 20 weight percent of the 2,6-isomer. Other typical isocyanatesinclude 4,4'-methylene-bis(phenylisocyanate),3,3'-bitolylene-4,4'-diisocyanate,3,3'-dimethoxy-biphenylene-4,4'-diisocyanate,naphthalene-1,5-diisocyanate, hexamethylene diisocyanate, 1,4-phenylenediisocyanate, polyphenylene polymethylene isocyanate, etc. The amount ofisocyanate employed in the preparation of the polyurethane foams shouldbe sufficient to provide at least about 0.7 NCO groups per hydroxylgroup present in the reaction system. An excess of isocyanate compoundcan be conveniently employed, however, the use of a large excess isgenerally undesirable due to the high cost of the isocyanate compounds.It is preferable, therefore, to employ no greater than about 1.5 NCOgroups per hydroxyl group, and still more preferably from about 0.9 toabout 1.3 NCO groups per hydroxyl group.

In preparing the polyurethane foams, the polyol containing the phenolicamide stabilizer of this invention is reacted with the organicisocyanate in the presence of a foaming agent and a reaction catalyst.The foaming agent can be any of those known to be useful for thispurpose, e.g., water. The amount of foaming agent employed can be variedwithin a wide range. Generally, water is employed in an amount of fromabout 0.1 to about 10 parts by weight of the polyol.

The catalyst used in preparing the polyurethane foams can be any ofthose known to be useful for this purpose or mixtures thereof, includingtertiary amines and metallic salts. Typical tertiary amines includeN-methyl morpholine, N-hydroxyethyl morpholine, triethylene diamine,dimethyl ethanolamine, tetramethylbutane diamine, trimethylamine,triethylamine, etc. Typical metallic salts include the salts ofantimony, tin, and iron, e.g., dibutyltin dilaurate, stannous octanoate,etc. Generally speaking, the catalyst is employed in an amount rangingfrom about 0.1 to about 2.0 weight percent based on the weight of thepolyol.

It is preferred in the preparation of the polyurethane foams of thepresent invention to employ minor amounts of a surfactant in order toimprove the cell structure of the polyurethane foams. Typical of suchsurfactants are the silicon-based surfactants as disclosed, e.g., inU.S. Pat. No. 2,834,748 and in the book "Rigid Plastic Foams" by T. H.Ferrigno (1963), Reinhold Publishing Company. Other suitable compoundsuseful as surfactants include synthetic detergents such as oxyethylatednonyl phenol and other ethylene oxide and glycidol-based surfactants.Generally up to about 2 parts by weight of the surfactant is employedper 100 parts by weight of polyol.

Various additives can also be employed in preparing the foam which serveto provide different properties. Fillers, e.g., clay, calcium sulfate,barium sulfate, ammonium phosphate, etc., can be added to lower cost andimprove physical properties. Dyes can be added for color and fibrousglass or synthetic fibers can be added for strength. In addition,plasticizer, deodorants and flame retardants can be added.

The following examples are illustrative of the invention.

Microwave Oven Scorch Test

The Microwave Oven Scorch Induction Test (MOSIT) is a rapid,reproducible bench scale test for the effectiveness of antioxidantpackages which correlates well with observed results from large scaleindustrial foams. This procedure utilizes small hand-mixed foam buns toevaluate the effectiveness of antioxidant packages. Because small bunswill dissipate the internal heat more rapidly than foam buns produced onan industrial scale, a microwave oven is used to uniformly heat the foambun by radiant energy, rather than conducting heat through it by the useof a convection oven. The microwave oven promotes heating of the smallfoam bun under conditions which have the ability to create reproduciblescorch within the foam bun. Because humidity and temperature in thelaboratory can affect results, it is advisable for antioxidant packagecomparisons to be run concurrently.

The formulation used to prepare foam bun samples is listed in Table Iand is typical of what is currently used by many major U.S. polyolmanufacturers in similar type testing.

                  TABLE 1                                                         ______________________________________                                        Flexible slabstock foam formulation.                                          ______________________________________                                        Stabilized polyether polyol*                                                                           200.0 grams                                            Water (de-ionized) 10.0 grams                                                 Amine catalyst (Dabco 33-LV, Air Products) 0.5 grams                          Surfactant (Niax L-620, Air Products) 2.0 grams                               Flame retardant (Fyrol FR-2, AKZO) 12.0 grams                                 Tin catalyst (Dabco T-10, Air Products) 0.4 grams                             Toluene Diisocyanate (TDI-80/20, Olin) 124.5 grams                            TDI index 109                                                               ______________________________________                                         *Polyether polyol  A 3,000 average molecular weight polyol, when received     contains a minimum stabilization of approximately 100 ppm butylated           hydroxytoluene (BHT). This polyol is then further stabilized with AO          package to be evaluated.                                                 

The microwave oven employed in this testing was a 700 watt WhirlpoolTimeMaster. Prior to testing the first foam bun, the microwave oven ispre-conditioned by placing a 1000 mL beaker containing 600 mL of waterin the microwave oven for 30 minutes at a power setting of 60%. A freshbeaker is returned to the microwave oven for 15 minutes at a powersetting of 60% prior to each additional foam bun tested. This procedureis carried out in order to maintain a constant temperature and humiditywithin the microwave oven during testing.

The prepared foam formulation is poured into a 10"×10"×5" cardboard boxand allowed to rise. Five minutes after the appearance of health bubblesacross the surface of the foam bun, the sides of the cardboard box areremoved. The foam bun is immediately placed into the preconditionedmicrowave oven. The foam is irradiated for a specified time (usuallyabout 15 minutes) at a power setting of 30%. The foam bun is removedfrom the microwave oven, and immediately placed into an air circulatingoven for 3 minutes at 125° C., to cure the hide of the foam. Uponremoval from the air circulating oven, the foam bun is immediately cutin half, perpendicular to the rise of the foam, and inspected for degreeof scorch. A rating of "0" indicates no scorch while a rating of "10"indicates very severe scorch. Two foams of each formulation wereprepared. The scorch ratings of each formulation were averaged to givethe results disclosed below.

EXAMPLE 1

This example illustrates the preparation and testing of the compound##STR5## Preparation:

To a 250 mL 3-neck round-bottom flask equipped with an overhead stirrer,a sub-surface nitrogen purge and a condenser, a mixture of 53.46 g(0.183 mol) of methyl 3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate with48.0 mL (0.366 mol) of 1-(2-aminoethyl)-piperazine and 0.94 g (0.0049mol) p-toluene sulfonic acid monohydrate was added. The reaction mixturewas then stirred at 140° C. for 15 hours with a moderate nitrogen purgeto produce a thick orange-yellow final product.

To the thick orange-yellow final product, 100 mL portion of reagentxylenes was added. The product was washed two times with 100 mL of hot(90° C.) 0.1 M sodium bicarbonate solution and then washed twice with100 mL hot (90° C.) de-ionized water. The solvent was removed using arotary evaporator. The final crude product was a light orange-yellowglassy solid at 25° C.

A 24 g portion of the final product was vacuum distilled. The distillatewas a light yellow, glassy solid at 25° C. with a melting point of 50 to55° C. A 5 g sample of the distillate was recrystallized from xyleneshaving a melting point of 109 to 111° C.

Testing:

a) The following polyether polyol samples were prepared:

1. Standard containing 2500 ppm BHT and 2000 ppm Naugard-445.

2. Experimental sample containing 2500 ppm of Example 1.

    ______________________________________                                        Results:                                                                        Polyol Sample 1 2                                                           ______________________________________                                        Naugard-BHT ppm    2500       0                                                 Naugard-445 ppm 2000 2000                                                     Example 1 0 2500                                                              Scorch Number* 2.0 2.0                                                      ______________________________________                                         *Scorch Number = 0-10, where 0 = no scorch and 10 = very severe scorch.  

b) A repeat of Test (a) was conducted. The following polyether polyolsamples were prepared:

1. Standard containing 2500 ppm BHT and 2000 ppm Naugard-445.

2. Experimental sample containing 2500 ppm of Example 1.

    ______________________________________                                        Results:                                                                        Polyol Sample 1 2                                                           ______________________________________                                        Naugard-BHT ppm    2500       0                                                 Naugard-445 ppm 2000 2000                                                     Example 1 0 2500                                                              Scorch Number* 1.0 1.0                                                      ______________________________________                                         *Scorch Number = 0-10, where 0 = no scorch and 10 = very severe scorch.  

The result of this test was that equivalent performance was repeated.

c) Thermogravimetric Analysis of Example 1 versus BHT

This experiment was conducted to determine the volatility of thephenolic amide stabilizer versus BHT.

Thermogravimetric Analysis (TGA) of neat antioxidants was a techniqueused to measure volatility. Approximately 10 mg of sample is weighedinto an aluminum sample cup and then placed inside the chamber of aPerkin-Elmer TGS-2 Thermogravimetric Analyzer. The chamber wasequilibrated to 160° C. under a nitrogen flow of 50 mL per minute, andrun isothermally for 250 minutes or until 100% weight loss of the sampleis experienced. A temperature of 160° C. was used since it approximatestemperatures reached during production of large scale industrial foams.

Results:

After 10 minutes at 160° C. with a nitrogen flow of 50 mL/minute, 72% ofthe BHT had volatilized. After 250 minutes, only 1.6 percent of Example1 had volatilized.

EXAMPLE 2

This example illustrates the preparation and testing of the compound##STR6## Preparation:

To a 100 mL 3-neck, round-bottom flask equipped with an overheadstirrer, a subsurface nitrogen purge and a condenser, 21.7 g (0.074 mol)of methyl 3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate with 21.5 g(0.137 mol) of decyl amine and 0.47 g (0.0025 mol) p-toluene sulfonicacid monohydrate was added. The mixture was stirred at 170° C. for 15hours with a moderate nitrogen purge.

15 mL reagent xylenes was then added to dissolve the final product. Theproduct was washed two times with a 50 mL portion of hot (90° C.) 0.1Msodium bicarbonate solution and then washed three times with 50 mLportions of hot (90° C.) de-ionized water. The solvent was removed usinga rotary evaporator and 27.7 g of a viscous yellow liquid was recovered.The liquid was crystallized over a two week period with the crystallizedproduct having a melting point of 52 to 56° C.

Testing:

The following polyether polyol samples were prepared:

1. Standard containing 2500 ppm BHT and 2000 ppm Naugard-445.

2. Experimental sample containing 2500 ppm Example 2 and 2000 ppmNaugard-445.

    ______________________________________                                        Results:                                                                        Polyol Sample 1 2                                                           ______________________________________                                        Naugard-BHT ppm    2500       0                                                 Naugard-445 ppm 2000 2000                                                     Example 2 0 2500                                                              Scorch Number* 3.0 3.0                                                      ______________________________________                                         *Scorch Number = 0-10, where 0 = no scorch and 10 = very severe scorch.  

These results indicate equivalent performance of the experimental andthe standard containing BHT.

EXAMPLE 3

This example illustrates the preparation and testing of the compound##STR7## Preparation:

To a 100 mL 3-neck round-bottom flask equipped with an overhead stirrer,a subsurface nitrogen purge and a 70° C. knock-back condenser, a mixtureof 35.0 g (0.120 mol) of methyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate with 23.2 g (0.180 mol) of 2-ethylhexyl amine and 0.16 glithium amide was added. The reaction mixture was stirred at 160° C. for15 hours with a moderate nitrogen purge.

The viscous light-yellow product was dissolved in 50 mL reagent xylenesand washed with 200 mL 0.3M HCl. The product was then washed five timeswith 200 mL portions of de-ionized water. A rotary evaporator was usedto remove the solvent and 42.1 g of a light yellow viscous liquid wasrecovered. The product was crystallized over a four week period with thecrystallized product having a melting point of 62 to 64° C.

Testing:

a) The following polyether polyol samples were prepared:

1. Standard containing 2500 ppm BHT and 2000 ppm Naugard-445.

2. Experimental sample containing 2500 ppm Example 3 and 2000 ppmNaugard-445.

    ______________________________________                                        Results:                                                                        Polyol Sample 1 2                                                           ______________________________________                                        Naugard-BHT ppm    2500       0                                                 Naugard-445 ppm 2000 2000                                                     Example 3 0 2500                                                              Scorch Number* 2.0 1.5                                                      ______________________________________                                         *Scorch Number = 0-10, where 0 = no scorch and 10 = very severe scorch.  

b) A repeat of Test (a) using PS-30 (a liquid amine commerciallyavailable from Uniroyal Chemical Co.) as the amine stabilizer.

The following polyether polyol samples were prepared:

1. Standard containing 2500 ppm BHT and 2000 ppm Naugard-445.

2. Experimental containing 2500 ppm Example 3 and 2000 ppm NaugardPS-30.

    ______________________________________                                        Results:                                                                        Polyol Sample 1 2                                                           ______________________________________                                        Naugard-BHT ppm    2500       0                                                 Naugard-445 ppm 2000 0                                                        Naugard PS-30 0 2000                                                          Example 3 0 2500                                                              Scorch Number* 3.00 2.75                                                    ______________________________________                                         *Scorch Number = 0-10, where 0 = no scorch and 10 = very severe scorch.  

There was a noticeable improvement in scorch protection using theexperimental stabilizer package versus the standard.

What is claimed is:
 1. A stabilized composition comprising an organicmaterial which is susceptible to degradation and in need ofstabilization to prevent or inhibit such degradation and a stabilizationeffective amount of at least one phenolic amide stabilizer compound ofthe general formula ##STR8## wherein n is 0 to 3, R₁ is alkyl of from 1to about 6 carbon atoms, it being provided that at least one of R₁ andR₂ is t-butyl R₃ is hydrogen and R₄ is alkyl of up to about 20 carbonatoms containing a heterocyclic group.
 2. The stabilized composition ofclaim 1 wherein the organic material which is susceptible to degradationis a polyether polyol.
 3. The stabilized composition of claim 1 whereinR₄ is alkyl containing a heterocyclic group derived from a heterocycliccompound selected from 2-(2-aminoethyl)-1-methylpyrrolidine,4-(2-aminoethyl)morpholine, 1-(2-aminoethyl) pyrrolidine,1-(2-aminoethyl)piperidine, and 1-(2-aminoethyl)piperazine.
 4. Thestabilized composition of claim 1 wherein R₁ and R₂ are t-butyl and R₄is alkyl containing a heterocyclic group derived from a heterocycliccompound selected from 2-(-2-aminoethyl)-l-methyl-pyrrolidine,4-(2-aminoethyl)morpholine, 1-(2-aminoethyl)pyrrolidine,1-(2-aminoethyl)piperidine, and 1-(2-aminoethyl)piperazine.
 5. Thestabilized composition of claim 1 wherein the phenolic amide stabilizeris N-[2-(1-piperazinyl)ethyl]-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionamide
 6. A method for stabilizing an organic material which issusceptible to degradation and in need of stabilization to prevent orinhibit such degradation which comprises adding thereto a stabilizingamount of at least one phenolic amide stabilizer of the general formula##STR9## wherein n is 0 to 3, R₁ is alkyl of from 1 to about 6 carbonatoms, R₂ is hydrogen or alkyl of from 1 to about 6 carbon atoms, itbeing provided that at least one of R₁ and R₂ is t-butyl R₃ is hydrogenand R₄ is alkyl of up to about 20 carbon atoms containing a heterocyclicgroup.
 7. The method of claim 6 wherein the organic material which issusceptible to degradation is a polyether polyol.
 8. The method of claim6 wherein R₄ is alkyl containing a heterocyclic group derived from aheterocyclic compound selected from2-(2-aminoethyl)-1-methylpyrrolidine, 4-(2-aminoethyl)morpholine,1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)piperidine, and1-(2-aminoethyl)piperazine.
 9. The method of claim 6 wherein R₁ and R₂are t-butyl and R₄ is alkyl containing a heterocyclic group derived froma heterocyclic compound selected from2-(2-aminoethyl)-1-methylpyrrolidine, 4-(2-aminoethyl)morpholine,1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)piperidine, and1-(2-aminoethyl)piperazine.
 10. The method of claim 6 wherein thephenolic amide stabilizer isN-[2-(1-piperazinyl)ethyl]-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionamide.
 11. A polyurethane foam obtained from a polyurethanefoam-forming reaction mixture containing as stabilizer for the foam aphenolic amide of the general formula ##STR10## wherein n is 0 to 3, R₁is alkyl of from 1 to about 6 carbon atoms, R₂ is hydrogen or alkyl offrom 1 to about 6 carbon atoms, it being provided that at least one ofR₁ and R₂ is t-butyl R₃ is hydrogen and R₄ is alkyl of up to about 20carbon atoms containing a heterocyclic group.
 12. The polyurethane foamof claim 11 wherein R₄ is alkyl containing a heterocyclic group derivedfrom a heterocyclic compound selected from 2-(2-aminoethyl)- 1-methylpyrrolidine, 4-(2-aminoethyl)morpholine,1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)piperidine, and1-(2-aminoethyl)piperazine.
 13. The polyurethane foam of claim 11wherein R₁ and R₂ are t-butyl and R₄ is alkyl containing a heterocyclicgroup derived from a heterocyclic compound selected from2-(2-aminoethyl)- 1-methyl-pyrrolidine, 4-(2-aminoethyl)morpholine,1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)piperidine, and1-(2-aminoethyl)piperazine.
 14. The polyurethane foam of claim 11wherein the phenolic amide stabilizer isN-[2-(1-piperazinyl)ethyl]-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionamide.